Update leveldb to version 1.8.0. Major changes:

Version 1.8:
  - Added utility to dump leveldb files.

Version 1.7:
  - Small fixes.

Version 1.6:
  - Mmap at most 1000 files on Posix to improve performance for large databases.
  - Support for more architectures (thanks to Alexander K.)
  - Some bugfixes.

Changes in the package:
  - Install shared library.